Evaporator, especially for high pressure steam



I June 4, 1935. VE. KOENEMANN El AL 2,004,075

EVAPORATOR, ESPECIALLY FOR HIGH PRESSURE STEAM Filed Jan. 4, 1952 3Sheets-Sheet l I Imuemiom a A I l: v Emmi'Koanemann Dy Kaxl Genaa/h June4, 1935. E. KOENEMANN ET AL 2,004,075-

7 EVAPORATOR, ESPECIALLY FOR HIGH PRESSURE ,STEAM Filed Jan. 4, 1932 3Sheets-Sheet 2 Inuanioz-s Etna! Kaanemamn Karl Gauze];

4: M, haw v M ihaivAfimmeys fig. 3

June 4, 1935. E. KOENEMANN El AL 2,004,075

EVAPORATOR, ESPECIALLY FOR HIGH PRESSURE STEAM Filed Jan. 4, 1932 5Sheets-Shet 3 Inuemfors Elma/1' Koelwmann y Kali Gan sta]:

their Akin/1710.79

* high boiling Patented June 4, 1935 UNITED STATES PATENT OFFHICEI'EVAPORATDR, ESPECIALLY FOR HIGH PRESSURE STEAM Ernst Koenemamr and KarlGensclr, Berlin,

Germany, assignors to Gesellschaft iiir Drucktransformatoren toren) G.in. b. IL, B ration of Germany (Koenemann-Transformaerlin, Germany, acorpo- 9 Claims.

This invention relates to an evaporator, especially for the generationof high pressure steam, heated by means of a liquid medium having apoint, as for instance a fused salt- :i like chloride of zincammoniacate, and has as its main object a particular model of such anevaporator in which water and steam are prevented from penetrating intothe heating medium through leakages at the points where the water tubesare joined to the collecting chambers by a rolling or welding process.Furthermore it is possible by our invention, in case of leakage. at anyof the joints between the water tubes and the heating jacket containingthe heating fluid, to easily perceive which joint is defective andtocalk it without difficulty. At the same time it is provided thatthedifierent degrees of expansion and contraction ;of the variousmembers of the evaporator do not cause detrimental stresses in thematerial. Further details of the invention are. hereinafter describedand illustrated in the attached drawings in which Figs. 1 and 2 showdiagrammatically one illustrative embodiment of the invention, Fig. 1being a longitudinal section through the evaporator, the upper part ofFig. 2 a plan seen from above, and the lower part of Fig. 2 a section atthe line II--II of Fig. 1. Figs. 3 and 4 show a second embodiment of theinvention, Fig. 3 being a side view of a part of the evaporator, andFig. 4 a section at the line IV-IV, of Fig. 3. Figs. 5, 6, 7 a r ustratea third embodiment of the invention, in ch-Fig. 5 is a side view of theevaporator, Fig. 6 aview from above, and Fig. 7 is a fractional sectionat the line VII--VH of Fig. 6, and Fig. 8 is a fractional section at theline VIlI-V]II of Fig. 5; Figs. 7 and 8 are drawn at a larger scale thanFigs. 5 and 6. g V

'll'the evaporator consists of the following main pa s: I

The water tubes I, the collecting chambers 2 and 3 into which the watertubes are inserted, and the heating jacket encasing the water tubesalong the greater portion-of their entire length.

In the model illustrated by Figs. 1 and 2 the water tubes are arrangedas two concentric circles. The collecting chambers 2 and 3 are smallvertical drums of comparatively small dimensions arranged in the. centreof the circle. The upper and lower ends of the water tubes are'curvedinward at their ends and are atpoint 6 fixed-to the drums 'by a rollingor welding process. The

heating jacket is a double wall cylinder consisting of the outer wall 4,the inner wall 'I' and the annular top and bottom plates 8 and 9. At A\the cylinder has a-longltudinal slot and therefore the outer and innercasings 4 and 'l are there connected with each other by casing plates I0and ll. a

The water tubes are inserted between the walls 4 and I of the jacket andperforate the top and bottom plates 8 and 9 at the points marked I2,where they leave the heating jacket. At the perforating points I2 thewater tubes are welded to the jacket, i. e. in any usual or suitable wayas by electric or flame welding or by rolling or expending the metal toform a rolled, expanded, or calked joint, or a stufiing box is insertedat each of these points. On the outer wall 4 are the 15 flanged socketsl3 and I4 through which the heating fluid is supplied and discharged.

This fluid is heated in a separate vessel and continually keptcirculating from the vessel to 20 the evaporator and back by means of apump. a The heating medium enters into the heating jacket through one ofthe sockets, flows along the water tubes and after having delivered heatto them is discharged from the heating jacket and returns to the heatingvessel. Heating vessel, pump and the pipe-lines connecting the heatingvessel and the heating jacket are not illustrated in the drawings.

The heat delivered by the heating fluid causes the water in the watertubes to evaporate. The mixture of steam and water resulting therefrom.flows into drum 2 where the main part of the water carried along iscollected and flows through the downcomer 5 to the lower drum 3 fromwhich it is supplied to the various water tubes. The steam is dischargedat the socket piece l5, subject, if necessary, to superheating in aspecial device and then supplied to a turbine or used for any "otherpurpose. The necessary feed-water is 40 supplied to the evaporatorthrough the socket piece I 6.

If guide-plates are arranged in the interior of the heating jacket todirect the flow of the heating liquid in such a manner that first of allonly a part of the water tubes are heated by the hot fluid delivered bythe heating ,vessel, and the remaining tubes are heated later on, then,owing to the difierence in temperature between heating liquid and waterbeing greater at the inlet then at the outlet, the quantity of steamproduced in the first-heated tubes is very much higher than thatproduced in the rest, which is only very small. One could therefore omitthe downcomersbecause the water tubes which are only moderately heatedwould serve as downcomers. In such a case or course these water tubesmust open into the drum 2 below water level.

The assembling of the evaporator can take place as follows:

The top and bottom plates provided with the necessary holes fortheuwater tubes are put over the water tubes not yet bent andprovisionally fixed at half height of the tubes, the ends of whichthereupon .are curved inward and finally;

fixed intothe drums 2 and 3 by a welding or rolling process. The top andbottom plates 8 and 9 are then brought into their correct position, the.tubes are welded on at the points where they perforate the plates, andafter that the. top and 1 bottom plates and the walls 8, I, I 0 and ofthe jacket are welded together or joined by riveting. The inner wall Iconsists of different sections which are inserted in the interiorthrough the slot A between the walls l0 and I I, and thereupon welded orriveted to form the cylindrical wall I of the jacket.

structing such evaporators, the new construction described hereinpossesses the following advantages: Should the rolled or welded pointsof junction 6 of the water tubes commence to leak the steam or waterseeping through will become noticeable at once, and the points ofleakage can be made tight without delay. Neither water nor steam cancome in contact with the heating liquid because the heating jacket isarranged in such a manner that it does not encase the points of junction6. This is an important advantage, as the steam would be liable todisintegrate the heating fluid, especially as the temperature occurringin practice ranges at 660 F. and higher and together with the heatingfluid would corrode the iron parts. This would happen with oils having ahigh boiling point, as well as with fusions'of salts. The same advantagewill be realized at points l2 where the water tubes perforate the topand bottom plates 8 and 9. of the heating jacket. In case of leakagesoccurring at these points no water or steam can enter the heatingjacket, even if some of the heating fluid should seepfout.

Above all the new design offers a possibility of repairing leakages atthe points of perforation by ,Je-welding or re-caulking, or byre-packing and tightening the stufling boxes, should the tubes beprovided with such stuffing boxes. All previous constructions lackedthis possibility because the points'where the water tubes perforate theheating jacket, are too close together to permit repairs. In ourconstructions as described hereinabove, the boiler tubes are arranged astwo concentric circles having such a diameter that all the water tubesof an evaporator can be accommodated. Consequently it becomes possibleto subject all perforations l2 to a careful control and continualsupervision, and the perforations are well accessible from alldirections and can be therefore worked upon for repairs with thenecessary tools.

The opening A forming a. slot along the heating jacket'is not onlyimportant for the purpose of an easy assemblage of the inner wall I, butit also makes it possible to compensate tension strains existing in thecasings of the jacket, which strains are due to possible differences oftemperature. Tensions between the jacket and water tubes on the onehand, and the drums connected with each other by the downcomer on theother hand,

are absorbed by the curve ends of the water tubes.

If necessary. the downcomer can be provided with acompensation neck suchas the neck 26 shown on Fig. 5,

In the illustrations 3 and I another model of the evaporator isdemonstrated. The corresponding parts of the evaporator are indicated bythe same indexes as in Figs. 1 and 2. The water tubes l are arrangedvertically and h e curved ends.

They open into the horizontal (1%: and 3 and ed in- The are welded on atthe points 6, or

tybes are grouped as 4 sections having two rows each. Each group ofpipes is encased in a boxlike heating jacket consisting of the sidewalls 4 and 1, the top and bottom plates 8 and 9, and the frontal platesl0 and II. The side plates 4 and I run parallel to the axes of thedrums. The I height of the boxes corresponds to the length of theheating tubes, their .width to the length of the drums 2 and 3, andtheir depth is somewhat wider than the sum of the distance between thetwo rows of tubes and their diameters. The

' points where the heating jacket is perforated by As compared with theusual methods of con-- the water tubes, are marked l2. Everyone of theabove mentioned four boxes has a flanged socket l3, and another socket Mfor the heating liquid at the other end of the box which is notillustrated. The steam is conveyed from the upper drum through thesocket piece IS, the feed water is supplied through socket piece iii ofthe lower drum. Upper and lower'drums are connected by severaldowncomers 5. I

The advantage of the invention is particularly evident in this manner ofconstruction. If all tubes would lead from drum 2 tothe lower drumwithin a single boxlike heating jacket and with all tubes lying closetogether as rows, a control of the rolled joints 6 and the points ofperforation I-2. would perhaps be possible, but a repair of the pointsof perforation would be impossible, if a leakage should occur. In thenew construction within each jacket not more than two rows of tubes arearranged. These jackets are at such a distance from each other that thepoints of perforation I! of the water tubes into the heating jacket arequite accessible and repair work can be carried out at any time.

The assembly of the evaporator can take place in the same manner asalready described in the first model of construction as shown in Figs. 1and 2. Here also one would first of all slide the top and bottom platesover the ,as yet straight water tubes. The water .tubes would thereuponbe curved at their ends and then be fitted to the drums by a rolling orwelding process. Now the top and bottom plates 8 and 9 are put intotheir correct position arid the side walls 4, 1, l0 and II are joined tothem by welding or riveting.

A third model is illustrated by Figs. 5, 6, 7 and 8.

The water tubes I are in this construction placed closely togetherforming a bundle of tubes encased by the cylindrical part d to which onthe top and bottom conical parts l'i are attached, and upon whichsubsequently the cylindrical parts l8 having a considerably largerdiameter than the part 4 are fixed. The parts 4, H and I8 form theheating jacket together with the top and bottom plates 8 and 9. Thedifferent parts 4, 11, I8, 8 and 9 of the heating jacket are eitherwelded or riveted together, or they are joined by flanges, as shown inour'drawings. The water tubes l ,are bent'outwards at their ends andemerge from the There are so many different planes that on each levelonly a restricted number of water tubes emerge from the jacket. On theother hand the diameter of the cylindrical section I8 is so large thateach of these perforations I 2 is so far distant from the next, thateveryone of them is easily accessible from all sides. The perforationsin each plane can be arranged vertically one below the.

other forming several groups, the perforations of each group beingsituated always on two closely neighboured generatrices of the cylinderl8. In the drawings they are alternating chevronwise from right to leftforming several groups of two I closely neighboured generatrices of thecylinder The number of planes can of course be varied, and a smaller orgreater number can be used. Of course then the diameterof thecylindrical part I 8 must be chosen in accordance smaller or larger, inorder that the distances of the perforation points be the same asbefore. The tubes leaving the jacket enter at 6 small chambers, 2 and 3,four of which are arranged on top, and four below.

From the chambers 2 downcomers 5 lead to the lower chambers 3. It is,however, advisable that the downcomers do not lead to that chamber whichis situated vertically below the upper chamber in question, but to aneighbouring one, whereby the downcomer 5 is provided with two curvedparts serving as compensating necks. The steam from the several chambers2, together with such water as has not separated out and passed into thedown comers 5, is injected through the pipe-lines l9 to the steam drum20. The steam is then delivered by the socket 2i. The deposited waterflows through pipe 22 into a small collecting vessel 23 into which thefeed water flows through the pipe 24. The water is supplied to the watertubes I through the pipe-lines 25 which connect the drum 23 with thelower chambers 3; The heating fluid enters the heating jacketthrough'the socket l3, and leaves it through the socket H or vice versa.The heating jacket is provided with a compensation rib 26 which servesto compensate tensions and stresses due to heat differences existingbewater or steam cannot seep into the heating fluid. Furthermore thepoints I2 where 'the water-tubes tween the heating jacket and the watertubes.

The mounting of the evaporator can take place so that part 4 and theconical parts I! of the heating jacket are slipped over the water tubesprior to the latter being curved. The cylindrical part I8 is made ofseparate parts welded or riveted to each other and with the water tubes.Inside of the heating jacket, the water tubes can be kept in theircorrect position by suitablejmeans.

This model of ,construction is superior to other constructions by itsparticularly'low rate of flow resistance regarding the heating fluidwithin the heating jacket. Another advantage is that all of the watertubes are arranged closely together, the

cubic contents of the heating jacket consequently being very low and therequired quantity of heating fluid thereby remaining small. Nevertheless the advantageous'features of other models have beenalsolmaintained in this our construction. The joints 6 between the watertu ",perforate the heating jacket, are at such a distance from eachother that all tubesare accessible near the points of perforation andcan'be repaired from every direction. V

Without altering the nature of this invention it'is also possible to putinto practiceother models of the invention. For instance in the modelillusaxis of the drum, and not said set readily accessible from tratedin Figs. 5, 6, 7 and 8 the water tubes can be passed through the top andbottom plates 8 and 9 of theheating jacket. In this case, however, itwould be advisable to arrange the points where the water tubes passthrough the heating jacket so that they form pairs of concentric circleswhich alternatingly are close together or far distant from each other.Annular collecting chambers would then replace the difierent smallcollecting chambers 2 and 3, one annular chamber to be arranged aboveand one below each heating jacket. v Furthermore as an alternative inthe model shown in the Figs. 3 and 4 the box-shaped heating jackets canalso be arranged at a 90 angle to the 7 parallel to this axis, as

is illustrated in Figs, 3 and 4.

It is thus clear thatour invention may be em- I multiplicity of watertubes arranged in a plurality of continuous rows extending within saidjacket and through a wall thereof, a collector spaced from said jacketand into which said water tubes lead, said water-tubesv having theirmultiplicity of points of passage through said jacket wall disposed soas to render all said points of passage through said jacket wall readilyaccessible from practically all directions.

2. An indirectly heated evaporator according to claim 1, the saiddisposition ofthe multiplicity of points of passage of said multiplicityof watertubes through said jacket being arranged in rows, and said rowsbeing arranged in one or more passage of said water-tubesthrougli's'aid' jacket beingin two rows, i. e. paired rows, with thetubes of the respective rows in alternating chevronwise arrangement,substantially as described.

4. An indirectly heated steam generator or the like, of the typecomprising upper and lower collector drums, upcomer tubes surrounded bya heating jacket and at least one downcomer tube; constructed with saidupcomer tubes arranged in a plurality'of continuous adjacent rowspassing through the wall of said jacket and traversing a sfiace beforepassinginto the collector drums, so t at leakage at either set ofpoints'of passing will' not result in leakage of heated fluid intoheating fluid or vice versa, and said omer tubes being groups with but asmall number, as two, rows to arranged at at least one of said sets ofpoints of passing so as to render all points of passing of practicallyall directions.

5. A heat exchanger of the class described, comprising a jacket having aportion of relatively.

small cross-section intermediate. its end portions and having its endportions enlarged to a relatively greater size, a multiplicity of tubesextending through said jacket and projecting through the walls of itsenlarged end portions, those -portions of said tubes lying within theintermediate portion of said jacket being arranged in relatively closelyspaced relation,

and those portions of the in a plurality of groups with but a smallnumber, as two, rows to the group, and the structure of said heatexchanger providing access to said groups at both sides thereof.

'7. A heat exchanger according to claim 5, said :tubes extending throughand beyond the walls of said jacket in two rows, 1. e. paired rows, withthe tubes of the respective rows in alternating chevronwise arrangement,and the structure of said heat exchanger providing access to said pairedrows at both sides thereof.

"8. An evaporator according to claim 1, said heating jacket having arelatively large portion and a relatively small portion, said tubeslying closely adjacent one another withinsaid relatively small portion,said tubes passing through the wall of the relatively large portion,said enlargement providing for separation of the tubes before theirpassage through said wall and thereby providing for their disposition asaforesaid.

9 An evaporator according to claim 1, said jacket having a centralportion and widened end portions, said tubes extending through saidcentral portion closely adjacent one another, and said tubes bendingwithin said widened end portions and extending through said jacket wallat points laterally of said widened end portions with the points ofpassage thereof disposed as aforesaid.

ERNST KOENEMANN. KARL GENSCH.

